LOTS of shape and construction changes from 1971 to 2015. Back in those days, there was zero tiltback of the headstock, too! They relied strictly on the break at the nut to the tuning pegs to keep the strings in the grooves. Nowadays it's something like 3º or so - not sure.
I would LOVE to try one of the older Ricky's with a thin neck. All the ones I've ever played have been pretty similar in feel, with minor variations in thickness / width. It'd be a trip to play one with a thin neck.

. It had probably been there longer than the bass.